1. Field of Invention
This invention pertains to a system for controlling the vibrato effect of a stringed musical instrument, such as a guitar, and in particular to a device which controls the movement of the instrument bridge in response to manipulation of the instrument's tremolo arm.
2. Description of the Relevant Art
There are known tremolo and/or vibrato devices. For example, Itoh U.S. Pat. No. 4,903,568 discloses a tremolo device for a guitar having a stabilizing plate and mounted spring to maintain an initial position of the tremolo arm.
Watson U.S. Pat. No. 3,382,749 discloses a tremolo device utilizing a single rod cylinder to inflate a diaphragm disposed on the guitar body.
Lohman U.S. Pat. No. 2,136,627 discloses a tremolo device for a guitar comprising an electric motor to impart a vibratory motion to the guitar strings.
Kusek U.S. Pat. No. 4,944,208 discloses an adjustable tremolo device for a guitar including a cam for controlling the operation of the individual strings.
Borisoff U.S. Pat. No. 4,928,564 discloses a tremolo stabilizing unit including springs for providing appropriate biasing.
Fender U.S. Pat. No. 4,724,737 discloses a tremolo unit including a rocker element and a spring for applying a bias.
Satoh U.S. Pat. No. 4,939,971 discloses a tremolo device for a guitar including a spring member to maintain the guitar bridge in an initial position.
The above-identified references, however, fail to disclose a tremolo unit for a stringed instrument having means for isolating the tuning of each string, a means for muting the instrument without affecting the tuning thereof, a means for generating a tremolo effect by rotating the tremolo arm about an axis substantially perpendicular to the instrument face, and/or wherein the pitch of the instrument strings may be both raised and lowered relative to string pitch when the tremolo arm is at rest.
A significant problem associated with prior tremolo systems is that prior systems at most only resist change in tension of all the strings when the tension in one string changes. In such systems, a balanced condition exists wherein the upwardly-directed forces acting on the instrument bridge by the instrument strings are balanced with the downwardly-directed spring forces acting on the bridge. It can easily be seen that a change in string tension in one string will upset this equilibrium between the forces acting on the bridge, resulting in the bridge being displaced and thus changing string pitch in all the strings. Tuning the instrument and maintaining a tuned instrument are quite difficult as a result. In addition, tremolo systems having latching mechanisms for locking the tremolo arm into a fixed position require some manipulation to activate and deactivate the latching mechanism which, during a musical performance, is quite inconvenient to perform.